Excessive alcohol use is becoming recognized as an emerging health-related problem especially among veterans returning from combats. There is a need for increased vigilance and action to identify and counsel these at-risk veterans. Unfortunately, we lack the reliable diagnostic tests to detect the dangerous levels of drinking. Such tests would be indispensable for screening and care for veterans with excessive alcohol use. We hypothesize that alcohol consumption at high levels elicits cellular and molecular responses whose sequelae are apparent through the appearance of unique and low- abundance proteins or protein fragments in the serum, or changes in the glycosylation status of serum proteins, or both. These molecules may be derived from a variety of tissues and cells and are unrelated to conventional/traditional markers of alcohol-induced liver injury. To test this hypothesis, we plan to pursue the following specific aims. SPECIFIC AIM # 1. Determine the effect of excessive alcohol drinking on the serum proteome by detecting, identifying, and comparing the relative quantity of serum proteins and carrier protein-bound peptides, proteins, and protein fragments and evaluate these as potential biomarkers. We will determine the difference in serum proteomes in subjects with excessive use of alcohol and 'non-risky drinker' controls and determine the 'window of assessment' of the levels of serum proteomes in veterans with alcohol use disorder undertaking alcohol rehabilitation treatment. SPECIFIC AIM # 2. Determine the protein glycosylation status of glycoprotein enriched fractions from sera obtained from the patients in Specific Aim #1. If successful, the results from this project will revolutionize the screening methods for veterans with excessive alcohol use. PUBLIC HEALTH RELEVANCE: RELEVANCE AND POTENTIAL IMPACT ON VETERANS HEALTHCARE This grant proposal is highly relevant to veteran's health. Increasing the sensitivity and specificity of biomarkers for recognizing recent, excessive use of alcohol (EUA) in Veterans is a timely goal of research. The proposed study is of importance given the expected increase in excessive alcohol use among veterans especially those returning from combats. The diagnosis of veterans with excessive alcohol use is hampered by the lack of tests that can detect/screen dangerous levels of drinking. In a specific setting such as pre-liver transplant evaluation, such tests would be even more beneficial to ascertain that patients with alcoholic liver disease continue their sobriety. Short term impact: The results of this study will help us i) understand the association between the levels of serum protein markers of interest and the amount of recent alcohol consumption and ii) understand the dynamic and 'window of assessment' of the protein markers of interest when subjects undergo alcohol rehabilitation treatment. Long term impact: The long term goal and principal significance of this proposal is to develop a more comprehensive screening protocol that would augment the current screening tool with AUDIT-C to identify veterans with excessive alcohol use and alcohol use disorder. The sensitivity of positive AUDIT-C scores to identify subjects with excessive alcohol use in the VA setting was 68% and 66% in men and women, respectively. This leads to the burden or cost of counseling veterans with false positive AUDIT-C screens. At present, the TLFB cannot be used efficiently in order to stratify and quantify the amount of alcohol consumption in veterans in the clinic setting because its careful use is far too time consuming. The results from proposed work will enable us to establish the threshold levels of baseline serum protein markers of interest as they relate to excessive consumption of alcohol. If successful, we believe that the results from this study will revolutionize the screening methods for excessive alcohol use in veterans.